Collapsing Honey Bee Colonies: Blame The Parasites?

The honey bee population of North America is in decline. That fact has even acquired an acronym, CCD, Colony Collapse Disorder. A number of theories have been advanced as to why honey bees are dwindling, including viruses, mites and various fungi.

This week, researchers at San Francisco State University published a paper with a finding that bees on their own campus have been invaded by parasitic flies, who lay their eggs in the bees abdomen which causes the bees to become disoriented - falling down drunk disoriented.

Andrew Core is the author of the study. We reached him by phone in Oregon. Thanks for being with us.

ANDREW CORE: Thank you for having me.

SIMON: So you're a graduate student at San Francisco State when you started noticing this?

CORE: That is correct. It was actually discovered in I believe 2008. My advisor, Dr. Hafernik, was actually collecting these bees off of a landing under a light, to feed praying mantis that he collected on a field trip. Well, he left a vial of these bees on his desk, forgetting to feed the praying mantis with them. And when he got back to the vial, he found that the parasites were also inside the vial - the larvae of the fly were inside the files.

SIMON: Help us understand how the bees behave. I guess you refer to it as zombie-like behavior.

CORE: Normally when insects are attracted to lights at nighttime, when it becomes light again they usually disperse. Well, we found that many of these bees would stay on the ground under the lights and crawl around disoriented, unable to stand up on their legs. And most of them would eventually die in place.

That led us to actually look at when the bees were coming out. And so, to do that, we clicked enclosures over the hive and found that the bees were actually leaving the hive at night. And that's one of the most important findings of the study, is that it's very unusual for honey bees to leave the hive at night. And we found an association between this odd nighttime abandonment and this parasite.

SIMON: Mr. Core, what can be done?

CORE: Well, coming up with an actual solution or a remedy to ridding the hives of the parasite will be one of the last steps, after really understanding how the parasites behave. One of the things that we want to look at is if the bees that are actually in inside the hive, if they are becoming parasitized. If a large number of bees within a hive became parasitized that could likely cause the collapse of a colony.

So, we have a lot of investigation to do as far as what bees within a hive are being parasitized, and what the overall effect is on the hive. So that's one of the many questions we have left to answer on this new parasite.

SIMON: Andrew Core, one of the authors of a study from researchers at San Francisco State University on one of the factors that might be driving bees from their hives.

Mr. Core, thanks so much.

CORE: Thank you for having me.

SIMON: This is NPR News. Transcript provided by NPR, Copyright National Public Radio.